1. Field of the Invention
This invention relates to an electric arc furnace control system for providing vertical displacement of the consumable electrodes to realize optimum operation.
2. Description of the Prior Art
Prior art systems for electric arc furnace control are responsive to arc current and arc voltage, the electrode position being regulated by maintaining a fixed ratio between arc voltage and arc current in accordance with well known impedance regulation technique. However, it has been recognized that the impedance alone does not provide accurate melting information by reason of the fact that melting power does not bear a linear relationship to arc impedance. U.S. Pat. No. 3,435,121 to Jackson teaches that the electrode or electrodes should be controlled by means of a control signal which is a function of the electrode melting power averaged over a period of time. Additionally, another signal is provided which is a function of the power factor of the power supplied to the furnace, compared with a desired power factor. These two signals, respectively functions of power and power factor, are then used to raise or lower the electrodes.